A question of safety

By Jeff Foust on 2009 October 22 at 8:02 am ET

Yesterday Sen. Richard Shelby (R-AL) spoke on the Senate floor about the impending release of the Augustine committee report and its discussion of safety—or, rather, the lack of it, in his view. An excerpt:

The Chairman of the Review of U.S. Human Space Flight Plans Committee, Norm Augustine, announced that safety would be paramount. Yet, from reviewing the preliminary information, there is only one area where mission safety was examined in the report. The Augustine report contained no safety comparison for the various vehicles considered by the panel and no risk assessment based on each option. The only safety issue identified was an assessment of how “hard” the panel thought each overall mission would be to achieve–not the safest means to complete the mission successfully. Since safety is the most important issue, these omissions are starling to some of us.

When making comparisons on the safety and performance of the various options, fundamental design differences cannot be lumped together and considered to be equal. Without an honest and thorough examination of the safety and reliability aspects of the various designs and options, the findings of this report are worthless. I would like to know why this blue ribbon panel did not examine these safety aspects.

Constellation’s vehicles have been planned and scrutinized by multiple stakeholders, all with a single goal in mind: to provide a safe and reliable human space flight system for our Nation.

The topic of safety same up Wednesday as well in a talk by Augustine committee member Jeff Greason at the International Symposium for Personal and Commercial Spaceflight in New Mexico. In the Q&A session after his speech, he was asked why the committee didn’t endorse Constellation as the “most viable” option “even though from a safety and mission assurance standpoint it’s clearly the best option.” Greason said that safety and mission assurance was considered by the Augustine committee, but that goes beyond simply the choice of launch vehicles.

“Launch is a relatively small contributor to the safety and mission assurance” of human missions to the Moon and beyond. “It is not negligible, it is not something you want to forget about, but it does not dominate the loss of crew probabilities.” Therefore, he said, it was a mistake to focus on further increasing the reliability of a relatively small aspect of overall mission risk, particularly if those choices lead you to take out safety systems in other components that because of mass restrictions. “These are false economies in terms of safety and mission assurance.”

Greason was also skeptical about the probabilistic risk assessments used to estimate the safety of various proposed systems. Most launch failures are not from random types of events, he said, but instead failures of design, testing, procedure, and the like. “If it was built wrong, it doesn’t work a lot of the time, no matter what you thought the probabilistic failure was.” The only way to “buy down” those failures, he said, is though flight experience, which is why “real boosters” have lower reliabilities than estimated when they were “paper boosters” still in the design phase.

“And the truth is, Ares 1 is, right now, a paper booster,” Greason continued. “And the further truth is, its projected launch rate is extremely low, so it will never get out of ‘infant mortality,'” that initial phase of non-probabilistic failures. “Even if Ares 1 were built exactly as planned, we would never find out whether its mature probabilistic risk assessment was or was not achievable as planned, because we would never get through the phase of life where we’re supposed to work out all the teething problems.”

18 comments to A question of safety

In addition, there are very real worries that Ares I would in fact be a very unsafe vehicle. The 45th Space Wing recently came out with a report that predicted an abort near max Q would be 100% fatal. The vibrations are a major problem and a risk to the crew. There was a lot of talk range safety wouldn’t even allow Ares I-X to be launched because they were afraid the vibrations might take out the abort system itself. And to make things worse the performance shortfall means removing things like radiation shielding from Orion which increases risk later on in the mission.

I’m glad that Jeff is keeping the record clear. The Ares-I safety argument, even if the PRAs are actually true (for the first time in engineering history), is as Jeff pointed out bogus. Launch safety has to drop below the 1/400 level before it starts meaningfully impacting the safety of a lunar mission. Once you have a decent vehicle with a decent track record and a decent LAS, NASA’s own numbers show that you should then turn your focus to the areas of the deep-space mission that are actually the most dangerous. Once you’ve gotten the odds of losing a crew on a complete mission down from the 1/50-1/60 that NASA currently predicts to something like 1/200 or so, then you can start sweating ascent reliability again. I mean really, when your overall odds of losing a crew are 1/50, do you really think it makes you look competent safety engineer to be wasting all your money trying to take a 1/1000 system (EELVs) to a 1/2000 system (theoretical best Ares-I numbers)?

As I note at my blog, Ares will be the safest vehicle. A system that costs so much you can barely afford to fly it won’t be able to kill very many people. In fact, it’s unlikely to ever fly, so it will be completely hazard free.

Nelson, simple repetition doesn’t render a statement valid. You seem to completely miss the point, which is that you don’t get safety from a paper design. You get it from experience of operations. Even if it meets NASA’s modest goals, Ares will never fly enough to be safe.

What does the expression have to do with Greason’s comments? His XCOR racers have flown safely to date, and there is no indication so far that XCOR’s suborbital vehicle design is unsafe.

“Ares I is a fundamentally one of the safest designs.”

How do you know? Evidence?

“However, Greason steadfastly refuses to comprehend the obvious.”

Appeals to the obvious make for poor and unsafe engineering. It was obvious for years to the Space Shuttle program that ET foam insulation shedding during ascent posed little or no risk to the orbiter. And then the Columbia accident happened.

When it comes to safe engineering, the devil is in the details. Provide evidence to back up your argument or don’t bother posting.

Shelby’s comments make no sense. The Augustine Committee left detailed issues of design safety to NASA, stating in the Summary Report that “any concepts falling short in human safety have simply been eliminated from consideration” in the Committee’s analysis.

So the Augustine Committee stands behind any of the vehicle options in its report as safe. Is Shelby arguing that he doesn’t trust NASA to execute a detailed, safe design or procurement from the options provided by the Committee? Does Shelby really want the Augustine Committee or some other non-NASA entity to be responsible for doing detailed design safety on NASA vehicles and procurements?

Goofy…

Sure would be nice if our elected representatives in the NASA states and districts actually bothered to comprehend the expert advice they’re given and think about what they’re saying before they say it — for once.

It is nice to see some one like Jeff Greason that is having a good dose of common sense! Based on this alone I would say that this committee appeared to be made of realists, not wishful thinkers, like some people seem to be in Alabama.

A little sigh of relief in this really strange worl of faith based HSF.

The only leg that Greason has to stand on is that the commercial sector has the potential, long range, of significantly reducing launch costs when a significant orbital space tourism takes off. However, that is many years away…

For a startup like him to use infant mortality or paper designs as an argument against Ares is nothing less than comical forensic suicide, from a debate perspective.

For a startup like him to use infant mortality or paper designs as an argument against Ares is nothing less than comical forensic suicide, from a debate perspective.

He made cogent, logical points. They would remain so if he was head of Boeing, or a janitor there. You seem to have an inordinate illogical respect for authority, while not being able to distinguish between good and bad arguments. What is actually invalid about what he said? Stop attacking the debater, and deal with the issues.

If I were in Greason’s shoes, I would make a long term argument that orbital space tourism will result in a significant reduction in launch costs and (eventual) improvemnts in safety.

I would argue that we (the USA) have an economic interest in making sure that this market does not instead fall into the hands of other nations.

I would argue that ISS crew services would be a way to jump start this fledgling industry.

For an XCOR company representative to question the competence or experience of NASA with regard to safely placing crew into orbit is as absurd as South Africa suggesting that Tokyo has a seriously high crime rate.

For an XCOR company to question the competence or experience of NASA to safely place crew into orbit is as absurd as South Africa suggesting that Tokyo has a seriously high crime rate…

what?

as the robot on Lost in Space use to say “it does not compute”…either the first statement or the comparison.

“Safety” is as much as anything is a science not guess work. So for instance one does not have to be a sailor to evaluate the failures of the Command structure on RMS Titanic nor does one have to have sailed a “boat” of that size to see the problems.

One can be a safety expert in say oil well off shore platforms (as the person from Shell was who the CAIB consulted) and make an accurate determination if the methodology used by NASA in the Columbia “event” was “safe”…

> For an XCOR company representative to question the competence or experience of NASA with regard to safely placing crew into orbit is as absurd as South Africa suggesting that Tokyo has a seriously high crime rate.

What?!? Nelson, you may want to spend some quality time with this site, which has a good explanation of several varieties of logical fallacies: